The present invention relates to the field of automatically controlled plotters that produce graphic information on a recording medium in response to a plot program. More particularly, the present invention relates to the method and apparatus for verifying the plot produced by a marking instrument with the plot program.
Automatically controlled plotters that utilize marking instruments such as pens, pencils, ink jets and other types of graphic marking instruments sometimes fail to accurately reproduce a programmed plot due to difficulties associated within either delivering or applying the marking material to the plotting paper or other recording medium. Where ink pens are utilized by the plotter, obstructions in the pens or dirt and grease on the paper prevent the ink from flowing freely from the pen onto the paper to produce a continuous, dark line of uniform width and intensity. The problem becomes more prevalent when higher plotting speeds are utilized. In such cases, the plot produced is of poor quality with lines that may have gaps or be badly faded in certain segments. A plot of poor quality may possibly lead to errors in interpretation.
It is accordingly a general object of the present invention to provide method and apparatus for verifying a plot produced on a recording medium with the program from which the plot was generated. It is a further object of the invention to identify defective portions of a plot so that they may be corrected or eliminated from the finished product of the plotting process.